Dual-cell display apparatus

ABSTRACT

The present disclosure describes a dual-cell display apparatus. The apparatus includes a first panel, and a second panel disposed in a first preset order relative to the first panel. The apparatus includes a memory storing instructions; and a processor in communication with the memory. When executing the instructions, the processor is configured to receive an image signal, and generate dimming data for the first panel according to the image signal. When executing the instructions, the processor is also configured to generate image data for the second panel according to the image signal, and generate backlight data for backlight control according to the image signal.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of InternationalApplication No. PCT/CN2019/115547 filed on Nov. 5, 2019, which claimspriority to Chinese Patent Application No. 201910272468.9 filed on Apr.4, 2019, the entire content of which is incorporated herein byreference.

TECHNICAL FIELD

The present disclosure relates to display technology, and in particularto a dual-cell display apparatus.

BACKGROUND

In recent years, with continuous development of display technology,people have increasing requirements for image quality, where an imagecontrast is an important consideration factor. Therefore, dual-celldisplay technology is proposed in the industry, that is, two liquidcrystal panels are stacked together, so that a brightness of a darkframe (i.e., a black picture or a dark picture displayed on thedual-cell display apparatus) is reduced through cooperation of upper andlower panels. In this way, a static contrast of a liquid crystaltelevision is significantly increased. In a dual-cell display apparatus,there is a need to improve brightness control of the dual-cell displayapparatus.

SUMMARY

The present disclosure provides a dual-cell display apparatus. Theapparatus includes a first panel, and a second panel disposed in a firstpreset order relative to the first panel. The apparatus includes amemory storing instructions; and a processor in communication with thememory. When executing the instructions, the processor is configured toreceive an image signal, and generate dimming data for the first panelaccording to the image signal. When executing the instructions, theprocessor is also configured to generate image data for the second panelaccording to the image signal, and generate backlight data for backlightcontrol according to the image signal.

BRIEF DESCRIPTION OF THE DRAWINGS

To describe examples of the present disclosure more clearly, drawingsrequired in descriptions of the examples of the present disclosure willbe briefly introduced below. It is apparent that the drawings describedbelow are merely some examples of the present disclosure and otherdrawings may also be obtained by those of ordinary skill in the artbased on these drawings without paying creative work.

FIG. 1A is a schematic diagram illustrating an exploded structure of adual-cell display apparatus according to some examples of the presentdisclosure.

FIG. 1B is a schematic diagram illustrating an exploded structure ofanother dual-cell display apparatus according to some examples of thepresent disclosure.

FIG. 2 is a block diagram illustrating a principle of a dual-celldisplay apparatus according to some examples of the present disclosure.

FIG. 3 is a block diagram illustrating a principle of a control systemof a dual-cell display apparatus according to some examples of thepresent disclosure.

FIG. 3A is a flowchart illustrating operations by a dual-cell processorof the dual-cell display apparatus according to some examples of thepresent disclosure.

FIG. 3B is a flowchart illustrating a process of generating dimming dataaccording to some examples of the present disclosure.

FIG. 4 is a block diagram illustrating a principle of a multi-pathbacklight drive in multi-partition backlight control according to someexamples of the present disclosure.

FIG. 5 is a flowchart illustrating an LED backlight peaking enhancementtechnology method according to some examples of the present disclosure.

FIG. 6 is a flowchart illustrating another LED backlight peakingenhancement technology method according to some examples of the presentdisclosure.

FIG. 7 is a schematic diagram of dividing a backlight partition intobacklight regions according to some examples of the present disclosure.

FIG. 8 is a schematic diagram illustrating a gain adjustment curve of abacklight value according to some examples of the present disclosure.

FIG. 9A is a block diagram illustrating a detailed principle of acontrol system of a dual-cell display apparatus according to someexamples of the present disclosure.

FIG. 9B is a flowchart illustrating a method of a control system of adual-cell display apparatus according to some examples of the presentdisclosure.

FIG. 10 is a schematic diagram illustrating 9×9 neighboring domainsaccording to some examples of the present disclosure.

FIG. 11 illustrates a brightness value adjustment curve according tosome examples of the present disclosure.

FIG. 12 is a flowchart illustrating a brightness driving methodaccording to some examples of the present disclosure.

FIG. 13 is a schematic diagram illustrating a maximum brightness value Lmax 2 of a modeling image (L max 2=25) relationship curve according tosome examples of the present disclosure.

FIG. 14 is a schematic diagram illustrating a brightness compensationfactor model according to some examples of the present disclosure.

FIG. 15 is a schematic diagram illustrating an entry according to someexamples of the present disclosure.

FIG. 16 is a block diagram illustrating a structure of a dual-cellbrightness adjustment apparatus according to some examples of thepresent disclosure.

FIG. 17 is a schematic diagram illustrating a dual-cell liquid crystaldisplay apparatus according to some examples of the present disclosure.

FIG. 18 is a flowchart illustrating a brightness driving methodaccording to some examples of the present disclosure.

FIG. 19 is a schematic diagram illustrating a region of a displayedimage according to some examples of the present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The examples of the present disclosure will be described below incombination with accompanying drawings in the examples of the presentdisclosure. It is apparent that the described examples are merely partof examples of the present disclosure rather than all examples. Otherexamples achieved by those of ordinary skill in the art based on theexamples in the present disclosure without paying creative work shallall fall within the scope of protection of the present disclosure.

In the descriptions of the present disclosure, it is to be understoodthat an orientation or position relationship indicated by terms such as“center”, “upper”, “lower”, “front”, “back”, “left”, “right”,“vertical”, “horizontal”, “top”, “bottom”, “inside” and “outside” is anorientation or position relationship shown based on the accompanyingdrawings, and is only used to facilitate describing the presentdisclosure and simplify the description rather than indicate or implythat a described apparatus or element should have a particularorientation or be constructed and operated in the particularorientation, and thus shall not be construed as limiting to the presentdisclosure.

In the descriptions of the present disclosure, it is to be noted thatterms “install”, “connection” and “connect” are to be broadlyunderstood, unless otherwise clearly specified and defined. For example,the connection may be a contact connection, or a detachable connection,or an integrated connection. Persons of ordinary skill in the art mayunderstand specific meanings of the above terms in the presentdisclosure according to a specific situation. FIG. 1A and FIG. 1B areschematic diagrams illustrating an exploded structure of a dual-celldisplay apparatus according to some examples of the present disclosure.FIG. 2 is a block diagram illustrating a principle of a dual-celldisplay apparatus according to some examples of the present disclosure.

As shown in FIG. 1A, FIG. 1B and FIG. 2, the dual-cell display apparatusincludes a backlight module 100, a first panel 200, a second panel 300and an adhesive layer 400 which are all stacked in order. The backlightmodule 100 is configured to provide a light source for transmitting, thefirst panel 200 is a light control panel for controlling a light fluxfor the light from the backlight module 100 into the second panel 300,the second panel 300 is a color panel for displaying an image, and theadhesive layer 400 is used to fix the first panel 200 and the secondpanel 300 together into an integral unit.

Referring to FIGS. 1A and 1B, along an A-A′ direction 199 of thedual-cell display apparatus, the first panel 200 includes a firstpolarizer 201 adjacent to the backlight module 100, a first liquidcrystal light valve layer 202 and a second polarizer 203 in order.Polarization direction (or the transmittance axis) of the firstpolarizer 201 and polarization direction of the second polarizer 203 areperpendicular to each other. The light from the backlight module 100 isconverted into a first polarized light after passing through the firstpolarizer 201. Then, the first polarized light enters the first liquidcrystal light valve layer 202. In this case, according to the contentsof the displayed image, the direction of the first polarized light isrotated by controlling liquid crystal in the first liquid crystal lightvalve layer 202 to rotate through voltage. Then, the first polarizedlight with a rotated angle enters the second polarizer 203 and convertsinto second polarized light. Since the polarization direction of thefirst polarizer 201 and the polarization direction of the secondpolarizer 203 are perpendicular to each other, the control of the lightflux entering the second panel 300 is realized. It is to be noted thatthe first panel 200 does not include a light filter. If the light fromthe backlight module 100 is white light, the first panel 200 is amonochromatic panel.

Referring to FIG. 1A, along the A-A′ direction 199 of the dual-celldisplay apparatus, the second panel 300 includes a third polarizer 301adjacent to the first panel 200, a second liquid crystal light valvelayer 302, a filter 303 and a fourth polarizer 304 in order.Polarization direction of the third polarizer 301 and polarizationdirection of the fourth polarizer 304 are perpendicular to each other.The polarization direction of the second polarizer 203 and thepolarization direction of the third polarizer 301 are parallel to eachother. When the second polarized light from the first panel 200 entersthe third polarizer 301, the second polarized light does not convert inpolarization direction and then enters the second liquid crystal lightvalve layer 302. According to the contents of the displayed image, thepolarization direction of the second polarized light is rotated bycontrolling liquid crystal in the second liquid crystal light valvelayer 302 to rotate through voltage. The second polarized light with arotated angle enters the filter 203 and changes into colored light.Then, the colored light enters the fourth polarizer 304 and is convertedinto third polarized light. Since the polarization direction of thethird polarizer 301 and the polarization direction of the fourthpolarizer 304 are perpendicular to each other, the control of the lightflux of the colored light is realized, thereby realizing color displayof an image.

When external water vapor enters between the first panel and the secondpanel, the water vapor will solidify into water drops due to temperaturechanges between the first panel and the second panel, thereby affectingthe display effect. The adhesive layer 400 bonds the first panel 200 andthe second panel 300 together in a surface attaching manner. The surfaceattaching refers to full attaching, that is, an adhesive layer is coatedon the whole surface. To avoid affecting light transmission, theadhesive layer 400 may be a transparent adhesive layer, such as anOptically Clear Adhesive (OCA) or an Optical Clear Resin (OCR). Toensure a bonding effect and avoid making the dual-cell thicker, thethickness of the adhesive layer is between 0.15 mm and 0.75 mm. In someexamples, the thickness of the adhesive layer is between 0.25 mm and 0.5mm.

It is to be noted that the first panel 200 includes a polarizer, forexample, the second polarizer 203, and the second panel 300 includes apolarizer, for example, the third polarizer 301. FIG. 1A illustrates acase where the first panel 200 and the second panel 300 each have twopolarizers. In other examples of the present disclosure, the first panel200 and the second panel 300 share a polarizer. FIG. 1B illustrates acase that the first panel 200 and the second panel 300 share onepolarizer. In a case that a display requirement is satisfied, saving onepolarizer may reduce costs of the display apparatus. As shown in FIG.1B, a difference from FIG. 1A, is that the dual-cell display apparatusdoes not include the third polarizer 301. In the display apparatus, thepolarization direction of the first polarizer 201 and the polarizationdirection of the second polarizer 203 are perpendicular to each other,and the polarization direction of the second polarizer 203 and thepolarization direction of the fourth polarizer 304 are perpendicular toeach other. Similar to a principle of an optical path of the dual-celldisplay apparatus shown in FIG. 1A, the second polarized light from thefirst panel 200 directly enters the second liquid crystal light valvelayer 302. According to the contents of the displayed image, thepolarization direction of the second polarized light is rotated bycontrolling liquid crystal in the second liquid crystal light valvelayer 302 to rotate through voltage. The second polarized light with arotated angle enters the filter 203 and changes into colored light.Then, the colored light enters the fourth polarizer 304 and is convertedinto the third polarized light. Since the polarization direction of thesecond polarizer 203 and the polarization direction of the fourthpolarizer 304 are perpendicular to each other, the control of the lightflux of the colored light is realized, thereby realizing the colordisplay of an image.

In the dual-cell display apparatus shown in FIG. 1B, the position of theadhesive layer 400 is not limited to locating between the secondpolarizer 203 and the second liquid crystal light valve layer 302, whichmay also locate between the first liquid crystal light valve layer 202and the second polarizer 203.

The first liquid crystal light valve layer 202 and the second liquidcrystal light valve layer 302 are similar in structure and include anupper substrate, a lower substrate and a liquid crystal box locatedbetween the upper substrate and the lower substrate.

The liquid crystal light valve layers in the first panel 200 and thesecond panel 300 both include a plurality of liquid crystal boxes.Similar to a principle of light control in the second panel 300 (thecolor panel), the first panel 200 takes a single pixel as an independentlight valve to realize pixel-level light control. Compared with adisplay apparatus with only one panel, the dual-cell display apparatushas two layers of pixel-level light control, thereby realizing a finercontrol. Since the first panel 200 realizes the pixel-level lightcontrol, compared with the single-cell display apparatus, a brightnessof a dark frame is significantly reduced through cooperation of thefirst panel 200 and the second panel 300, so that a problem that thedark frame has a certain brightness due to no absolute non-transmissionof the liquid crystal light valve layer in the single-cell displayapparatus is solved, thereby significantly increasing a static contrastof a liquid crystal display apparatus.

Since the first panel 200 realizes light control through the polarizerand the rotation of liquid crystal and the transmittance of thepolarizer is 38%-48%, the entire transmittance of the display apparatuswill be reduced. In the present disclosure, a resolution of the firstpanel 200 to be smaller than a resolution of the second panel 300, thatis, the number of pixels in the first panel 200 is set to be smallerthan the number of pixels in the second panel 300, to avoid aninsufficient display brightness of the display apparatus, resulting froma reduced transmittance of the light from the backlight module throughthe first panel due to using the dual-cell. A ratio of the number ofpixels in the second panel 300 and the number of pixels in the firstpanel 200 is not less than 4:1, for example, 4:1 and 16:1. That is, whenthe resolution of the second panel 300 is 8K, the resolution of thefirst panel 200 is 4K or 2K; when the resolution of the second panel 300is 4K, the resolution of the first panel 200 is 2K.

Specifically, in some examples of the present disclosure, the resolutionof the first panel 200 is 1920*1080, and the resolution of the secondpanel 300 is 3840*2160.

In some examples of the present disclosure, as shown in FIG. 2, tofurther increase the image contrast, the backlight module 100 adoptsmultiple backlight partitions to control. That is, a backlight source inthe backlight module 100 is divided into a plurality of backlightpartitions 101, and the brightness of each backlight partition 101 isdynamically changed according to brightness information contained in thedisplayed image information. A bright area in the image corresponds to ahigh backlight brightness, and a dark area in the image corresponds to alow backlight brightness. Compared with constant backlight provided bythe backlight module, problems that a pure black frame still has weaklight leakage and power consumption is large are solved by dynamicallyadjusting the backlight brightness, thereby further increasing abrightness contrast of the image shown in the dual-cell displayapparatus and improving the image quality.

In the dual-cell display apparatus, the problem that the black frameshown in the dual-cell display apparatus is not black enough is furthersolved by combining dual panels and the control of the backlightpartitions, thereby a display contrast of the image is better improved.

Next, the controls of the dual-cell display apparatus for the dualpanels and the multi-backlight-partition will be discussed below.

FIG. 3 is a block diagram illustrating a principle of a control systemin a dual-cell display apparatus according to some examples of thepresent disclosure. FIG. 3A is a flowchart illustrating operations by adual-cell processor of the dual-cell display apparatus according to someexamples of the present disclosure. As shown in FIG. 3, the dual-celldisplay apparatus includes a System on Chip (SOC), a dual-cellprocessor, a first panel, a first panel Timing Controller (TCON), asecond panel, a second panel Timing Controller (TCON), a backlightcontrol processor, a backlight driver and a backlight lamp. Thebacklight control processor is, for example, a backlight controlMicrocontroller Unit (MCU).

The SOC outputs an image signal, and the dual-cell processor receivesthe image signal (Operation S301 in FIG. 3A). The dual-cell processor isconfigured to generate dimming data for the first panel in response tothe image signal (Operation S302 in FIG. 3A), where the dimming data issent to the first panel timing controller, and the first panel timingcontroller performs drive control for the first panel according to thedimming data. The dual-cell processor is further configured to generateimage data for the second panel in response to the image signal(Operation S303 in FIG. 3A), where the image data is sent to the secondpanel timing controller, and the second panel timing controller performsdisplay control for the second panel according to the image data. Thedual-cell processor is further configured to generate backlight data forbacklight control in response to the image signal (Operation S304 inFIG. 3A), where the backlight data is sent to the backlight control MCU,the backlight control MCU generates control information, such as a dutyratio and an electric current, and then sends the control information tothe backlight driver, and the backlight driver realizes drive controlfor the backlight lamp according to the control information, such as theduty ratio and the electric current.

Descriptions will be made below with the resolution of the first panelbeing 1920*1080 (2K) and the resolution of the second panel being3840*2160 (4K).

A process of generating the dimming data is described below withreference to FIG. 3B. After receiving a 4K image signal from the SOC,the dual-cell processor firstly converts an RGB value of a pixel in theimage into a first brightness value (Y) of the pixel, and then generatesa second brightness value corresponding to the pixel of the first panelby performing down-sampling processing for Y. In this way, resolutionreduction processing from 4K to 2K is realized (Operation S305 in FIG.3B). Then, Y contrast enhancement is performed according to the secondbrightness value, where the Y contrast enhancement includes brightnessenhancements of a local region and an entire region. Specifically, alocal brightness adjustment factor and a global brightness adjustmentfactor are determined by performing statistics processing for thebrightness values of the local region and the brightness values of aglobal image according to the second brightness value, and the Ycontrast enhancement is performed according to the second brightnessvalue, the local brightness adjustment factor and the global brightnessadjustment factor. Next, the brightness of a medium-high brightness areais increased by performing enhancement processing for the medium-highbrightness area according to areas with different contrasts in an image.Then, edge blurring processing is performed for the medium-highbrightness area, so that the smooth transition is realized betweenregions with different brightnesses in a frame by performing edgeblurring processing for the medium-high brightness area (Operation S306in FIG. 3B). In some examples of the present disclosure, smoothing maybe performed by spatial filtering, so that a problem of unsmooth lightwaveforms resulting from the liquid crystal boxes split in the firstpanel and isolation columns between the liquid crystal boxes is solved.Finally, the dimming data generated through the above operations istransmitted to the first panel timing controller (TCON) through a LowVoltage Differential Signaling (LVDS) interface, and the first paneltiming controller performs drive control for the first panel accordingto the dimming data.

A process of generating the image data is described below. Afterreceiving a 4K image signal from the SOC, the dual-cell processorperforms RGB contrast enhancement for the pixel to obtain a global imagebrightness statistical value for generating the dimming data, andperforms entire and local RGB contrast enhancements according to theglobal image RGB value and the local region RGB value, so that a blackarea on the display image is blacker, and a bright area is brighter,thereby increasing the entire contrast of the image. Further, to bettermaintain the brightness of a low-medium-brightness area when thebrightness of the first panel is reduced, corresponding imagecompensation is performed for the displayed image according tobrightness information of the first panel. In this way, the displayedimage with the brightness lost when the displayed image passes throughthe first panel, is compensated on the second panel. Thefinally-generated image data is transmitted to the second panel timingcontroller (TCON) through a V-By-One (VBO) interface, and the secondpanel timing controller performs drive control for the second panelaccording to the image data.

In some examples of the present disclosure, the multiple partitionscontrol technology and the dual-cell technology are combined. If thetraditional backlight control is directly combined with a dual-cellplatform, two modules are completely independent. At this time, thecharacteristics of the dual-cell platform (the first panel will reducethe backlight transmittance) is not considered in the backlight control,therefore, the backlight control is easy to be dark. Further, morebacklight partitions will cause more serious dark tendency. Therefore, aprocess of generating the backlight data in the present disclosure isdescribed below.

A down-sampling module is added after the spatial filtering of the firstpanel. The down-sampling module directly down-samples the original1920*1080 to a target backlight partition number, and then, performstime filtering. That is, blended data is obtained by blending thebacklight value of the current frame with the backlight value of theprevious frame. Then, the blended data is written into a RAM, and thenread out from the RAM to finally obtain the backlight data. The obtainedbacklight data is transmitted to the backlight control MCU through aSerial Peripheral Interface (SPI). The backlight control MCU generatesdimming information, such as a duty ratio and an electric current, andthen sends the dimming information, such as the duty ratio and theelectric current to the backlight driver, and the backlight driverregulates the drive control of the backlight lamp according to thedimming information, such as the duty ratio and the electric current.

The combination of the multiple backlight partitions technology and thedual-cell technology is realized in the above manner, so that a localbacklight lamp is as bright as possible, thereby enabling the dual-celldisplay apparatus to transmits more brightness and saving hardwareresources.

FIG. 4 is a block diagram illustrating a principle of multiple backlightdrive in a multiple partitions backlight control according to someexamples of the present disclosure. As shown in FIG. 4, the backlightcontrol MCU processes the brightness information of each backlightpartition, searches a mapping table pre-stored in a partition mappingunit of the backlight control MCU, and adjusts the duty ratio of eachbacklight partition according to an obtained coordinate position of thebacklight partition at the same time. The duty ratio of the backlightpartition is adjusted as follows: the backlight control MCU sendsbacklight duty ratio data of each backlight partition to the backlightdriver, for example, a Pulse-Width Modulation (PWM) driver, and a PWMdriver generates a corresponding PWM drive signal to drive a backlightsource (a light-emitting diode (LED) string). If necessary, thebacklight control processor sends electric current data to the PWMdriver which then adjusts and drives the electric current of thebacklight source according to the electric current data and a presetreference voltage V_(ref). Generally, the PWM driver is formed bycascading a plurality of chips, and each chip further drives the PWMdriver output current to LED strings.

Further, in the dual-cell display apparatus, the first panel reduces thelight transmittance, therefore the backlight control is easy to be dark,which is disadvantageous for brightness in a bright frame. Therefore, insome examples of the present disclosure, on the basis of performingbacklight partitions control for the backlight module, the bright areain the image is highlighted by dynamically increasing the brightnessesof the backlight partitions of the bright frame and a conventionaldisplay frame based on the backlight peaking enhancement technology,thereby further increasing the image contrast and an image layeringsense.

As shown in FIG. 5, specific steps are described below. At step 1001, abacklight value of each backlight partition is calculated. At step 1002,an average value of all backlight values is calculated. At step 1003, abacklight gain value may be determined according to the average value,for example, by means of a preset gain curve lookup table. At step 1004,the control information for controlling the backlight module may begenerated according to the backlight gain value. For example, the finalbacklight value is output by multiplying all backlight values by thebacklight gain value. Through the above gain processing operations, thebright area of the image is highlighted, thereby improving the contrastof the image. The above steps may be implemented in the backlightcontrol MCU.

Based on this, the contrast and the layering sense of the image may befurther increased by adopting an optimized backlight value enhancementtechnology. The following specific steps are as shown in FIG. 6 and FIG.7: at step 2001, N backlight partitions are divided into M backlightregions, where N is not equal to M, and M and N are integers greaterthan 1; at step 2002, a gain value corresponding to each backlightregion is inquired according to the average value of the backlightvalues of the backlight partitions contained in each backlight regionand the preset gain curve; at step 2003, the backlight values of Nbacklight partitions are adjusted according to the obtained M gainvalues. Different gain values are inquired for different backlightregions to realize different dimming control of different degrees forthe backlight regions of the backlight partitions, thereby increasingthe brightness contrast and the layering sense of the displayed image ina display process. The above steps may be implemented in the backlightcontrol MCU.

FIG. 8 is a schematic diagram illustrating a gain adjustment region of abacklight value according to some examples of the present disclosure. InFIG. 8, an abscissa is a backlight value in a value range of [0, 255],and an ordinate is a gain value in a value range of [1,+∞). However, insome examples, the value range of the gain value is set to [1, 2]according to an actual power setting requirement; further, the gainvalue is not limited to an integer, and thus may also be a non-integer.The gain adjustment curve is divided into a low-brightness enhancementinterval, a high-brightness enhancement interval and a power controlinterval. When the average value of the backlight values in thebacklight region is low, a corresponding gain value is in thelow-brightness enhancement interval. Along with a change of a displayedcontent in the backlight region, when the average value of the backlightvalues in the backlight region is in an appropriate threshold range, thegain value is in the high-brightness enhancement interval. Thehigh-brightness area in the image is well highlighted by adjusting thebacklight value according to the gain value of the high-brightnessenhancement interval. When the average value of the backlight values inthe backlight region is high, because the brightness of the entire imagein the backlight region is sufficiently high, it is not required toenhance the backlight value again. On the contrary, because of powerconsumption, it is required to decrease the gain value. Since theaverage values of the backlight values in different backlight regionsare different, a determined gain value is also different. By adjustingthe backlight value with the gain value, the brightness contrast of theimage is increased and the layering sense of the image becomes obviousin the displaying process.

The brightness control and the display control of the dual-cell displayapparatus and the combination of the dual-cell technology and thedynamic backlight control technology in the display apparatus are bothrealized by including a processor with the above functions in thedual-cell display apparatus.

Descriptions will be made to the processes of enhancing Y contrast andRGB contrast below by starting from RGB-Y. A second pixel is on thesecond panel, and a first pixel is on the first panel.

FIG. 9A is a block diagram illustrating a detailed principle of acontrol system in a dual-cell display apparatus according to someexamples of the present disclosure. As shown in FIG. 9B, a method 900for enhancing the Y contrast and the RGB contrast includes the followingsteps 901-904.

At step 901, converting an RGB value of a second pixel into a brightnessvalue (a Y value) of the second pixel.

An RGB color space used mostly in a computer corresponds to red, greenand blue correspondingly, and different colors are formed by adjustingratios of three-color components. Generally, these three colors arestored by using 1, 2, 4, 5, 16, 24 and 32 bits. In some examples of thepresent disclosure, the RGB component is represented by 8 bits, that is,the maximum brightness value is 255.

Generally, the RGB value is converted into the Y value (the brightnessvalue) based on the following formula.Y=0.299R+0.587G+0.114B

In some scenarios, the Y value calculated by the above method is notreasonable. For example, when the displayed image is a pure blue frame,the RGB value is (0,0,255), and the Y value obtained through the aboveformula is 29. In this case, the brightness value (the Y value) oftransmitted light will be much reduced compared with the RGB value(0,0,255) in the pure blue frame.

Therefore, to enhance the contrast, a maximum value of the R, G and Bvalues is selected as the Y value. In this way, the Y value using amaximum value of the R, G and B values is much increased compared withthe Y value calculated by using the conversion formula in the pure blueframe (0,0,255). When the RGB value is only converted into the Y value,the use of the maximum value of the RGB values is reasonable. At thistime, the brightness value Y is calculated based on the followingformula.Y=MAX(R,G,B)

At step 902, down-sampling a brightness value of the second pixel to abrightness value of a first pixel.

The RGB value of each second pixel of the displayed image is convertedinto the brightness value of the second pixel by the above method, andthen, a corresponding brightness value of the first pixel is generatedby down-sampling the brightness value of the second pixel.

In some examples of the present disclosure, for example, the secondpanel has pixels of 4 k, that is, the second panel has the second pixelsof 3840*2160. The first panel has the first pixels of 1920*1080.Correspondingly, pixels of 2 k is obtained by down-sampling pixels of 4k, that is, small squares of 1920*1080 are generated. The first pixelsare in one-to-one correspondence with the small squares of the secondpanel. The brightness value of each first pixel is calculated in amanner as follows: 4K brightness values are scaled based on a principlethat every four brightness values are scaled to one brightness value.Like general scaling, a set containing brightness values of the firstpixels of 1920*1080 is finally generated by using a maximum brightnessvalue of four pixels, an average brightness value of four pixels, aminimum brightness value of four pixels and a middle brightness value offour pixels.

At step 903, determining a local brightness adjustment factor and aglobal brightness adjustment factor by performing statistics processingfor the local region brightness values and the global image brightnessvalues according to the brightness value of each first pixel.

The global brightness adjustment factor includes: a global brightnessdown-adjustment factor global_min_y and a global brightnessup-adjustment factor global_max_y.

A process of calculating global_min_y includes: determining the maximumbrightness value P_frame_max, the average brightness value P_frame_avgand the minimum brightness value P_frame_min of the displayed image bytraversing the brightness value set of the first pixels.

Specifically, the maximum brightness value P_frame_max, the minimumbrightness value P_frame_min and the average brightness valueP_frame_avg of the image are obtained by traversing the brightness valueset of the first pixels, where the maximum brightness value and theminimum brightness value are not actual values but obtained according tothe statistics processing. Whether the number of pixels of grayscale 0sum=gray[0] is greater than the number of pixels of a preset grayscaleis determined from 0-grayscale (that is, a brightness value that isequal to 0 in the image). If not, accumulation is performed from thenumber of pixels of grayscale 0 to the number of pixels of grayscale 1,that is, sum_num=gray[0]+gray[1], until the condition is satisfied. Atthis time, the grayscale value is P_frame_min. Similarly, whether thenumber of pixels of grayscale 255 sum=gray[255] is greater than thenumber of pixels of the preset grayscale is determined from thegrayscale 255. If not, accumulation is performed from the number ofpixels of grayscale 255 to the number of pixels of grayscale 254, thatis, sum_num=gray[255]+gray[254], until the condition is satisfied. Atthis time, the grayscale value is P_frame_max. For example, the numberof pixels of the minimum grayscale value is preset to 8. When there isonly one pixel of grayscale 0, the number of pixels of grayscale 1 is 4;when the number of pixels of grayscale 2 is more than 3, the minimumbrightness value P_frame_min is set to a grayscale value 2. Therefore,interference and jump are avoided.

Where global_min_y=f(P_frame_min), global_min_y is a function relatingto P_frame_min. Similarly, where global_max_y=f(P_frame_max),global_max_y is a function relating to P_frame_max. A hardwareimplementation method may be a Look Up Table (LUT) method.

Optionally, the global brightness adjustment factor is calculated byblack area determination of an image background, where the black areadetermination of the image background includes:

-   -   initializing back_black_near_flag=0; and    -   calculating sum_gray_cont.

Specifically, a process of calculating sum_gray_cont includes: findingthe black area of the image background after performing histogramstatistics processing for the image, where the number sta-gray[k] ofpixels distributed between the brightness values Gray_TH0 and Gray_TH1is large and greater than NUM_TH0 (a preset value), and the number ofbrightness values between Gray_TH0 and Gray_TH1 is small, which isgenerally not greater than a threshold number TH0; counting the numbercont satisfying the condition that sta-gray[k] is greater than or equalto NUM_TH0 by counting sta-gray[k] between Gray_TH0 and Gray_TH1according to the distribution of brightness values; and counting anaccumulation value sum_gray_cont of sta-gray[k] under the condition thatcont is less than or equal to TH0.

For example, it is assumed that Gray_TH0=12, Gray_TH1=20 andNUM_TH0=3000. Thus, the number sta-gray[k] of pixels corresponding tothe brightness values of 12, 13, 14, 15, 16, 17, 18, 19 and 20 iscounted. As a result, the brightness values with sta-gray[k] beinggreater than or equal to 3000 are counted as the brightness value 13 andthe brightness value 14. Therefore,sum_gray_cont=sta-gray[13]+sta-gray[14].

If the sum_gray_cont is greater than or equal to sum_TH (a presetvalue), this frame of image is determined as an image with thebackground being the black area, and back_black_near_flag is set to 1 atthis time.

global_min_y is calculated by using two different f(P_frame_min)according to whether back_black_near_flag is 1;

if (back_black_near_flag=1), global_min_y1=f1(P_frame_min);

if (back_black_near_flag=0), global_min_y2=f2(P_frame_min),

where global_min_y1>global_min_y2, and f1 and f2 are function curves.

The process of calculating global_min_y is global_min_y=f(P_frame_min),which is linearly adjusted. For example,f(P_frame_min)=(255−P_frame_min). Similarly, a process of calculatingglobal_max_y is global_max_y=f(P_frame_max), which is linearly adjusted.For example, f(P_frame_max)=(255−P_frame_max).

Other non-linear adjustments may also be adopted. Considering hardwareimplementation, division is processed by the Look Up Table (LUT) method,thereby converting division into multiplication.

The local brightness adjustment factor includes: a local brightnessdown-adjustment factor local_min_y and a local brightness up-adjustmentfactor local_max_y.

m*n neighboring domains are selected by taking any first pixel as acenter. The brightness value of the first pixel and the brightnessvalues of the m*n neighboring domains constitute a local regionbrightness value set.

Each first pixel corresponds to one coordinate value (i, j). As shown inFIG. 10, with the position of the first pixel as the center of the m*nneighboring domains, the m*n neighboring domains may be 9*9 neighboringdomains.

The maximum brightness value P_local_max(i, j), the average brightnessvalue P_local_avg(i, j) and the minimum brightness value P_local_min(i,j) of the local region are determined by traversing the brightness valueset of each square in the local region.

Generally, the minimum brightness value and the maximum brightness valueof the local region are obtained by searching data of all positionpoints once, and the average brightness value of the local region isobtained by accumulating the brightness values of all first pixels ofthe local region into a sum and dividing the sum by the total number offirst pixels of the local region.

A process of calculating local_min_y(i, j) is similar to the process ofcalculating global_min_y, which will not be described in detail herein.

A process of calculating local_max_y(i, j) is similar to the process ofcalculating global_max_y, which will not be described in detail herein.

At step 904, calculating a brightness drive signal corresponding to thefirst pixel according to the brightness value of each first pixel, thelocal brightness adjustment factor and the global brightness adjustmentfactor. The brightness drive signal is used to adjust a transmittance ofa corresponding pixel of the first panel, and the global brightnessadjustment factor is also used to adjust the output brightness value ofa corresponding pixel of the second panel. The dimming datacorresponding to the first pixel is calculated through the followingsteps 9041-9043.

At step 9041, a global brightness adjustment value is calculated.

For a brightness value P(i, j) of any first pixel, if P(i,j)<P_frame_avg, the global brightness adjustment value is:P_out_global(i,j)=(P_frame_avg−(P_frame_min−global_min_y))/(P_frame_avg−P_frame_min)*(P(i,j)−P_frame_avg)+P_frame_avg,where P_out_global(i, j) is the global brightness adjustment value, andglobal_min_y is the global brightness down-adjustment factor.

For the brightness value P(i, j) of any first pixel, if P(i,j)=P_frame_avg, the global brightness adjustment value is:P_out_global(i,j)=P_frame_avg.

For the brightness value P(i, j) of any first pixel, if P(i,j)>P_frame_avg, the global brightness adjustment value is:P_out_global(i,j)=(P_frame_avg−(P_frame_max+global_max_y))/(P_frame_avg−P_frame_max)*(P(i,j)−P_frame_avg)+P_frame_avg,where global_max_y is the global brightness up-adjustment factor.

A specific adjustment result is as shown in FIG. 11, where x-axis isP(i, j), and y-axis is the global brightness adjustment valueP_out_global (i, j).

At step 9042, a local brightness adjustment value is calculated.

For the brightness value P(i, j) of any first pixel, if P(i, j) is lessthan P_local_avg(i, j), the local brightness adjustment value is:P_out_local(i,j)=(P_local_avg(i,j)−(P_local_min(i,j)−local_min_y(i,j)))/(P_local_avg(i,j)−P_local_min(i,j))*(P(i,j)−P_local_avg(i,j))+local_avg(i,j),where P_out_local(i, j) is a second brightness adjustment value, andP_local_min_y(i,j) is the local brightness down-adjustment factor.

If P(i, j) is equal to P_local_avg(i, j), the local brightnessadjustment value is:P_out_local(i,j)=P_local_avg(i,j).

If P(i, j) is greater than P_local_avg(i, j), the local brightnessadjustment value is:P_out_local(i,j)=(P_local_avg(i,j)−(P_local_max(i,j)+local_max_y(i,j)))/(P_local_avg(i,j)−P_local_max(i,j))*(P(i,j)−P_local_avg(i,j))+P_local_avg(i,j).

At step 9043, the brightness drive signal is calculated as follows:P_out(i,j)=weight_local(i,j)*P_out_local(i,j)+weight_global*P_out_global(i,j);weight_local(i,j)−weight_global=1;orP_out(i,j)=weight_local*P_out_local(i,j)+weight_global(i,j)*P_out_global(i,j)+weight_org*P(i,j);weight_local(i,j)+weight_global+weight_org(i,j)=1.

In the above formulas, weight_org(i, j) is an adjustment coefficient,P_out(i, j) is the brightness drive signal, weight_local(i, j) is alocal brightness weight coefficient, and weight_global is a globalbrightness weight coefficient.

A process of calculating the local brightness weight coefficient in theabove formula is described below.

N local modeling regions are selected on the first panel. The localmodeling region includes: a modeling brightness value i of a firstmodeling pixel, modeling brightness values of neighboring domains (m*n)of the first modeling pixel and a local brightness weight coefficientweight_local(i, j)_(modeling) corresponding to the first modeling pixel.

The local modeling region further includes a modeling brightnesscomplexity, i.e., includes an average value A_(modeling) of anappearance frequencies h_(g)(i)_(modeling) of the modeling brightnessvalue i, a power value Power_(modeling) of the appearance frequencyh_(g)(i)_(modeling) of the modeling brightness value i and an entropyvalue Entropy_(modeling) of the appearance frequency h_(g)(i)_(modeling)of the modeling brightness value i of the local modeling region.

A specific calculation process includes: counting the appearancefrequency h_(g)(i)_(modeling) of the modeling brightness value i of thelocal modeling region by using a histogram;

$\begin{matrix}\begin{matrix}{\mspace{79mu}{{{{Average}\mspace{14mu}{value}\text{:}\mspace{14mu} A_{modeling}} = {\frac{1}{M_{modeling}}{\sum\limits_{i}{{ih}_{g}(i)}_{modeling}}}};}} \\{\mspace{79mu}{M_{modeling} = {m_{modeling} \times n_{modeling}}}}\end{matrix} & (a) \\{\mspace{79mu}{{{Power}\mspace{14mu}{value}\text{:}\mspace{14mu}{Power}_{modeling}} = {\sum\limits_{i}\left\lbrack {h_{g}(i)}_{modeling} \right\rbrack^{2}}}} & (b) \\{{{Entropy}\mspace{14mu}{value}\text{:}\mspace{14mu}{Entropy}_{modeling}} = {- {\sum\limits_{i}{{h_{g}(i)}_{modeling}{{{lgh}_{g}(i)}_{modeling}.}}}}} & (c)\end{matrix}$

Constructing a weight_local(i, j)_(modeling)=A_(modeling),Power_(modeling), Entropy_(modeling)) curve as a first local brightnessweight coefficient curve.

For any first pixel, the average value A(i, j), the power value Power(i,j) and the entropy value Entropy(i, j) of the appearance frequencyh_(g)(i) of the local region brightness value i corresponding to thefirst pixel are calculated according to the local region brightnessvalue corresponding to the first pixel, and then, the local brightnessweight coefficient weight_local(i, j) corresponding to the first pixelis calculated by substituting A(i, j), Power(i, j) and Entropy(i, j)into the weight_local(i, j)_(modeling)=A_(modeling), Power_(modeling),Entropy_(modeling)) curve.

Optionally, a second local brightness weight coefficient curve isfurther obtained through the following calculation. P local modelingregions are selected on the first panel, and the local modeling regionincludes: a modeling brightness value of the local modeling region and alocal brightness weight coefficient corresponding to a second modelingpixel. The modeling brightness value of the local modeling regionincludes: a modeling brightness value of the second modeling pixel and amodeling brightness value of a neighboring domain of the second modelingpixel.

A first modeling frequency set is generated by counting the appearancemodeling frequencies of the modeling brightness values of differentsecond modeling pixels in different local modeling regions; a secondmodeling frequency set is generated by traversing the first modelingfrequency set and deleting the modeling frequency smaller than a presetfrequency; the modeling number of the modeling brightness valuescontained in the second modeling frequency set is counted, and thesecond local brightness weight coefficient curve is constructedaccording to the modeling number of each local modeling region and thelocal brightness weight coefficient.

For any first pixel, the number of brightness values with the frequencygreater than the preset frequency in the local region brightness valuescorresponding to the first pixels is counted, and the local brightnessweight coefficient corresponding to the first pixel is calculatedaccording to the above number and the second local brightness weightcoefficient curve.

Specifically, P local modeling regions are selected on the first panel,and the first modeling frequency set is generated by calculating theappearance frequency h_(g)(i)_(modeling) of each brightness value ineach local modeling region respectively; the second modeling frequencyset is generated by traversing the first modeling frequency set anddeleting the frequency smaller than the preset frequency; the numbercount_(modeling) of brightness values contained in the second modelingfrequency set is counted; theweight_local_(modeling)=f(count_(modeling)) curve, that is, the secondlocal brightness weight coefficient curve, is constructed.

The appearance frequencies h_(g)(i) of different brightness values iscounted according to the local region brightness value set correspondingto any first pixel, and the second frequency set is generated traversingthe first frequency set and deleting the frequency smaller than thepreset frequency, and then, the number count(i, j) of brightness valuescontained in the second frequency set is counted and then the localbrightness weight coefficient weight_local(i, j) corresponding to thefirst pixel is calculated by and substituting the count(i, j) into theweight_local_(modeling)=count_(modeling)) curve.

The number count of h_(g)(i)>NUM_th0 is counted. NUM_th0 is the presetfrequency, and NUM_th0 is generally 3000. For example, when theresolution of the first panel is, for example, 1920×1080, the range ofcount is 0-1920×1080. The count is set to an independent variable of theabscissa, weight_local(i, j) is set to a dependent variable of theordinate, and the numerical range of the local brightness weightcoefficient weight_local(i, j) is [0, 1].

When the histogram statistics processing is performed for the localmodeling region, the consumption of resources is still relatively large.To further simplify the hardware implementation method, an example ofthe present disclosure provides another method of calculating the localbrightness weight coefficient weight_local(i, j).

Specifically, N local modeling regions are selected on the first panel.If the brightness value of any first pixel in the local modeling regionis p(i, j)_(modeling), the brightness values of two first pixelsbordering the first pixel, i.e., a brightness value p(i+1, j)_(modeling)of No. 1 first pixel and a brightness value p(i, j+1)_(modeling) of No.2 first pixel, are determined.

Calculations are performed according to the following formulas.

$\begin{matrix}{{{p\_ diff0}\left( {i,j} \right)_{modeling}} = {{{{local\_ pixel}\left( {i,j} \right)_{modeling}} - {{local\_ pixel}\left( {i,{j \pm 1}} \right)_{modeling}}}}} \\{{{p\_ diff1}\left( {i,j} \right)_{modeling}} = {{{{local\_ pixel}\left( {i,j} \right)_{modeling}} - {{local\_ pixel}\left( {{i \pm 1},j} \right)_{modeling}}}}} \\{{{p\_ sum}{\_ diff}\left( {i,j} \right)_{modeling}} = {\sum\limits_{i = 0}^{n - 1}{\sum\limits_{j = 0}^{m - 1}\left( {{{P\_ diff}\left( {i,j} \right)_{modeling}} + {{diff}\left( {i,j} \right)}_{modeling}} \right)}}} \\{\mspace{79mu}{{{{p\_ avg}{\_ diff}\left( {i,j} \right)_{modeling}} = {{p\_ sum}{\_ diff}{\left( {i,j} \right)_{modeling}/\left( {m \times n} \right)}}},}}\end{matrix}$where p_diff0(i, j)_(modeling) and p_diff1(i, j)_(modeling) are adifference between the brightness value of the first pixel and thebrightness value of the No. 2 first pixel and a difference between thebrightness value of the first pixel and the brightness value of the No.1 first pixel respectively. A modeling brightness characteristicp_sum_diff(i, j)_(modeling) or p_avg_diff(i, j)_(modeling) is obtainedbased on the above formula, where m*n refers to the number of pixelscontained in the local region brightness value set.

A p_weight_local_(modeling)=f(p_sum_diff_(modeling)) curve or ap_weight_local_(modeling)=f(p_avg_diff_(modeling)) curve is constructed.

For the brightness value p(i, j) of any first pixel, p_sum_diff(i, j)corresponding to the p(i, j) is calculated, and the local brightnessweight coefficient weight_local corresponding to the first pixel iscalculated by substituting the p_sum_diff(i, j) into thep_weight_local_(modeling)=f(p_sum_diff_(modeling)) curve; or thep_avg_diff(i, j) corresponding to the p(i, j) is calculated, and thenthe local brightness weight coefficient weight_local corresponding tothe first pixel is calculated by substituting the p_avg_diff(i, j) intothe p_weight_local_(modeling)=f(p_avg_diff_(modeling)) curve.

In some examples, when local sampling is performed, if the central pointis in upper several rows and left several columns or in lower severalrows and right several columns of the image, the data taken by atemplate comes from outside the range of the image, and a duplicatingmethod is used in the template.

For example, the template is of a size of 9*9 and the central point is(0,0). The upper left corner is filled with the data of the point (0,0);the data in a row of the upper right corner and a column of the lowerleft corner is duplicated from the data in the first row and the firstcolumn of the template respectively; the data of the lower right cornerdirectly comes from data in the original image; a data filling format isin the form of symmetrical duplication. A column is taken as an example.The template includes columns of −4, −3, −2, −1, 0, 1, 2, 3 and 4. thecolumn −4 is duplicated from the data of the column 4 rather than thedata of the column 1, the data of the column −3 is duplicated from thedata of the column 3, the column −2 is duplicated from the data of thecolumn 2, and the column −1 is duplicated from the data of the column 1.The data in the upper right corner is also duplicated from the data of(0,0).

Similarly, a method of calculating the global brightness weightcoefficient weight_global may be referred to the above method ofcalculating the local brightness weight coefficient, which will not bedescribed herein.

Optionally, the processor contained in the dual-cell apparatus isfurther configured to: determine a local color adjustment factor bycounting local region RGB value according to RGB value of each secondpixel; determine a global color adjustment factor based on global imagebrightness values of the second panel and global RGB value of the secondpanel; and calculate a color drive signal corresponding to the secondpixel according to the RGB value of the second pixel, the local coloradjustment factor and the global color adjustment factor, where thecolor drive signal is used to adjust the RGB value of the second pixelof the second panel.

The first panel is used to receive the brightness drive signal andadjust a transmittance corresponding to the first pixel according to thebrightness drive signal.

The second panel is used to receive the color drive signal and adjustthe RGB value corresponding to the second pixel according to the colordrive signal.

The processing of medium-high-brightness enhancement is described below.

A data flow processed by Y contrast enhancement is received forsubsequent processing. Specifically, as shown in FIG. 12, the methodincludes the following steps S101-S104.

At step S101, a brightness value set of a displayed image is determined.

At step S102, an average brightness value Lavg1 and a maximum brightnessvalue L max 1 of the displayed image are determined according to thebrightness value set.

It is to be noted that the calculated maximum brightness value L max 1of the displayed image is not a maximum value of all brightness valuesbut a maximum value in a statistical sense. Generally, after thestatistics processing is completed, a grayscale of which the number ofpixels is not zero is obtained from grayscale 255 to grayscale 0, andthe number of pixels contained in each grayscale is required to exceed aparticular threshold (for example, 0.1% of the total number). If thenumber of pixels of the grayscale does not satisfy the requirement, thenumber of pixels of the grayscale is accumulated to the number of pixelsof the next grayscale, until the number of pixels of the grayscalesatisfying the condition is obtained. The grayscale is the maximumbrightness value L max 1 of the displayed image. For the calculation ofthe average brightness value Lavg1 of the displayed image, if thebrightness values of the pixels of one displayed image are allaccumulated and then divided by the number of pixels, a data bit widthof the accumulated sum will generally overflow. Particularly, when thedata bit widths are 10 bits and 12 bits, for convenience of calculation,the average brightness value of each row in the displayed image isfirstly calculated, and then the average brightness values of n rows arecalculated, and then averaging is performed for average brightnessvalues of the n rows and finally the average brightness value Lavg1 ofthe entire displayed image is obtained.

In some examples, the display apparatus generally displays the displayedimage based on a light blending principle. Therefore, each pixel isfurther divided into three sub-pixels, i.e., R, G and B. Threesub-pixels correspond to different brightnesses, and thus thebrightnesses corresponding to different pixels are also different. Inthis example, when histogram statistics processing is performed for thebrightnesses, the brightness in each pixel is a maximum brightness valuecorresponding to original brightnesses of three sub-pixels in the pixel.During the statistics processing, only one sub-pixel with the maximumbrightness value is counted, which leads to a less statistics amount anda less calculation amount than a calculation amount of all sub-pixels.In this case, the statistics processing and the calculation are simplerand faster. On the other hand, the pixel brightness corresponding to thesub-pixel with the largest original brightness in the R, G and Bsub-pixels, is used as the statistic amount, which retains originaldisplayed image information of an input displayed image as possible,compared with use of the pixel brightness corresponding to the lowest ormiddle value of the original brightnesses of three sub-pixels. Thus, theinformation loss of the input displayed image is less and the displayeffect of the displayed image is better.

At step 103, a brightness compensation factor is calculated according tothe average brightness value and the maximum brightness value of thedisplayed image.

Specifically, the brightness compensation factor is obtained bysubstituting the average brightness value and the maximum brightnessvalue of the displayed image into a brightness compensation factormodel.

In some examples of the present disclosure, the brightness compensationfactor model is pre-constructed. The brightness compensation factormodel is constructed based on the maximum brightness value L max 2 ofthe modeling image and the average brightness value Lavg2 of themodeling image. A process of constructing the brightness compensationfactor model includes steps 1031-1035.

At step 1031, n groups of modeling images are selected, where the Lamx2s of different groups of modeling images are same, and the L max 2 isthe maximum brightness value in the modeling image.

For example, n groups of modeling images are selected, where thebrightness value of the modeling image is in a range of 0-255.Correspondingly, the maximum brightness value of the modeling image isin the range of 0-255, and the average brightness value of the modelingimage is in the range of 0-255.

The maximum brightness values of the selected n groups of modelingimages are uniformly distributed in the interval of 0-255. Specifically,if 11 groups of modeling images are selected, the maximum brightnessvalues L max 2 in 11 groups of modeling images are 1, 25, 51, 76, 102,127, 153, 178, 204, 229 and 255 respectively.

At step 1032, a Lavg2 set is generated by calculating the Lavg2 of eachmodeling image in any group of modeling images, where the Lavg2 is theaverage brightness value in the modeling image.

For example, L max 2=25. When L max 2=25, the Lavg2 of the correspondingmodeling image is any value of 25, 24, 23, 22, 21, 20, 19, 18, 17, 16,15, 13, 14, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1 and 0.

The Lavg2 set is formed by Lavg2s of all modeling images in the group ofL max 2=25.

At step 1033, a y set is calculated according to the group of L max 2=25and the Lavg2 set, where the y is the brightness compensation factor.

For the group of L max 2=25, one y is calculated according to one L max2=25 and one Lavg2, and one y set is obtained according to L max 2=25and a plurality of Lavg2s.

At step 1034, a y=f(Lavg2, L max 2=25) relationship curve is establishedaccording to the group of L max 2=25, the Lavg2 set and the y set.

For the group of L max 2=25, the y=f(Lavg2, L max 2=25) relationshipcurve is as shown in FIG. 13.

At step 1035, n relationship curves are constructed as the brightnesscompensation factor model.

To increase the contrast of the displayed image, in the examples of thepresent disclosure, the contrast of the display image is determined,which is generated based on the pixel brightness value of the displayedimage, and the brightness compensation factor of the whole displayedimage is determined according to the contrast. Generally, an image withthe large contrast requires an increased contrast as possible.Therefore, the low-scale brightness of the displayed image isappropriately decreased, the high-scale brightness is appropriatelyincreased. Original characteristics are maintained for a scenario with asmall contrast as possible.

An example of the present disclosure further provides a method ofcalculating an average brightness value of each modeling image withineach group. Specifically, a first brightness value set is generated bycounting brightness values of different pixels of the modeling image; asecond brightness value set is generated by traversing the firstbrightness value set and deleting the brightness value smaller than apreset brightness value; an average brightness value of the secondbrightness value set, that is, the average brightness value of themodeling image, is calculated.

For example, the preset brightness value is 10, and the pixels with thebrightness value being less than 10 are deleted in the process ofcalculating the average brightness value of the displayed image. Forexample, the brightness values of three pixels of 10 pixels are lessthan 10. In this case, the method of calculating the average brightnessvalue is to obtain a result as the average brightness value of themodeling image by summing up the brightness values of the remaining 7pixels and dividing the obtained sum by 10.

Specifically, the finally-constructed 11 y=f(Lavg2, L max 2=n)relationship curves are referred to FIG. 14, where a numerical valuecorresponding to the y-axis is the brightness compensation factor, anumerical value corresponding to the x-axis is Lavg2, and the above 11relationship curves form the brightness compensation factor model.

The step of calculating the brightness compensation factor bysubstituting the L max 1 and Lavg1 into the brightness compensationfactor model includes steps 1036-1037.

At step 1036, if a L max 1=L max 2 relationship curve exists for thebrightness compensation factor model, the brightness compensation factoris obtained according to a corresponding relationship between the Lavg1s and the brightness compensation factors.

For example, when L max 1=25 and Lavg1=13 in the displayed image, onerelationship curve L max 1=L max 2 exists in the brightness compensationfactor model shown in FIG. 14. In the relationship curve of L max 2=25,the obtained brightness compensation factor corresponding to Lavg2=13 isthe brightness compensation factor of the displayed image.

At step 1037, if the L max 1=L max 2 relationship curve does not existin the brightness compensation factor model, the brightness compensationfactor is calculated through the following several steps.

At step 10371, calibration points index0, index1, index2 and index3 of(L max 1, Lavg1) and weight coefficients weight0, weight1, weight2 andweight3 corresponding to the calibration points are calculated.

At step 10372, brightness compensation factors date0, date1, date2 anddate3 corresponding to index0, index1, index2 and index3 are determinedby traversing the brightness compensation factor model.

At step 10373, the brightness compensation factor is obtained accordingto y=(Σ_(i=0) ³ data(i)×weight(0)>>16.

A process of calculating the calibration points and the weightcoefficients is described below.step_h;index_x=(Lavg×step_h)>>14;m ₀=(step_h×Lavg)&0x3fff;m ₁=(1<<14)−m ₀;step_v;index_y=(Lmax×step_v)>>14;n ₀=(step_v×Lmax)&0x3fff;n ₁=(1<<14)−n ₀;index0=index_y×N+index_x;index1=index_y×N+(index_x+1);index2=(index_y+1)×N+index_x;index2=(index_y+1)×N+(index_x+1);weight0=(m ₁ ×n ₁)>>12;weight1=(m ₀ ×n ₁)>>12;weight2=(m ₁ ×n ₀)>>12;weight3=(m ₀ ×n ₀)>>12.

In the above formulas, step h refers to a valuing step length in anaverage value direction, step v refers to a valuing step length in amaximum value direction, and N is the number of relationship curves.

For example, for any displayed image, if Lavg1 is calculated as 30 and Lmax 1 is calculated as 60, the average brightness value and the maximumbrightness value of the displayed image form a point (30, 60).

A specific reference is made to FIG. 15 if an entry is established forthe modeling image based on Lavg2 and L max 2. The entry is establishedwith Lavg2 as an abscissa and L max 2 as an ordinate.

With continuous reference to FIG. 15, a process of determining thecalibration points of (30, 60) includes: determining two Lavg2 valuesadjacent to 30 in the entry as 25 and 51; and determining two L max 2values adjacent to 60 in the entry as 51 and 76, thereby forming fourcalibration points index0, index1, index2 and index3.

The specific calculation process is: assuming thatstep_h=160;Index_x=(30×160)>>14;m ₀=(160×30)&0x3fff;m ₁=(1<<14)−m ₀;step_v=160;Index_x=(60×160)>>14;n ₀=(160×60)&0x3fffn ₁=(1<<14)−n ₀index0=index_y×11+index_x;index1=index_y×11+(index_x+1);index2=(index_y+1)×11+index_x;index2=(index_y+1)×11+(index_x+1).

In the above formulas, index0 is (25, 51); index1 is (51, 51); index2 is(25, 76); index3 is (51, 76); the brightness compensation factors data0,data1, data2 and data3 corresponding to four calibration points (25,51), (51, 51), (25, 76) and (51, 76) are determined in the brightnesscompensation factor model shown in FIG. 14. The weight coefficientscorresponding to four calibration points respectively are:weight0=(m ₁ ×n ₁)>>12;weight1=(m ₀ ×n ₁)>>12;weight2=(m ₁ ×n ₀)>>12;weight3=(m ₀ ×n ₀)>>12;brightness compensation factor=(Σ_(i=0) ³data_i×weight_i)>>16.

At step S104, the brightness drive signal corresponding to the displayedimage is calculated according to the brightness compensation factor.

Optionally, the steps of calculating the brightness drive signalcorresponding to each frame of displayed image according to thebrightness compensation factor includes: obtaining the brightness drivesignal corresponding to each frame of displayed image by compensatingthe brightness corresponding to each frame of displayed image accordingto the brightness compensation factor; and determining whether thebrightness drive signal is greater than or equal to the maximumbrightness value of the display apparatus.

It is assumed that M is the maximum brightness value of the displayapparatus. If the display apparatus with an 8-bit channel includes 256brightnesses and the maximum brightness value is 255, M is 255. If thedisplay apparatus with a 10-bit channel includes 1024 brightnesses andthe maximum brightness value is 1023, M is 1023.

The enhanced brightness value exceeds a range, and thus the value isrequired to be limited within a data range. Generally, for 8-bit data,if the brightness value obtained by multiplying the current brightnessvalue by its respective y (the brightness compensation factor) isgreater than 255, let output brightness value be 255.

If the brightness value is less than 255, the brightness drive signal isobtained by calculation according to the brightness compensation factor.

In another example, a structure of a dual-cell display apparatus is asshown in FIG. 16. The dual-cell display apparatus includes: a lightemitting source 1, a first panel 3 and a second panel 4. Transmittancesof different transmission regions of the first panel 3 are different.Therefore, the light emitting from the light emitting source 1 presentsdifferent brightnesses in different regions after passing through thefirst panel 3 to obtain an effect that different regions of onedisplayed image have different background brightnesses. When the firstpanel 3 adjusts the brightness, an RGB coordinate system is generallyconverted into one of a YCbCr coordinate system, a YUV coordinatesystem, an HSV coordinate system and an HIS coordinate system, therebyenhancing brightness and chromaticity respectively to achieve theadjustment of an overall contrast of the displayed image. FIG. 17 is anexemplary diagram illustrating the first panel 3 according to someexamples of the present disclosure. The first panel 3 has a firsttransmission region and a second transmission region. Transmittance ofthe first transmission region is 20%, and transmittance of the secondtransmission region is 80%. The light emitting from the light emittingsource 1 provides background light for the second panel 4 after passingthrough the first panel 3. At this time, the background light of aregion in the second panel 4 corresponding to the first transmissionregion is darker and the background light of a region in the secondpanel 4 corresponding to the second transmission region is brighter.

For the above dual-cell display apparatus, the brightness of thebackground light of a fixed region of the second panel 4 is constant.When the brightnesses of a first frame of image and a second frame ofimage are obviously different, a high-brightness area cannot behighlighted, resulting in a distorted medium-high-brightness area. Tosolve the above problem, a brightness driving method is providedaccording to a second aspect of an example of the present disclosure.The method is applied to the first panel 3 of the dual-cell displayapparatus. As shown in FIG. 18, the method includes steps S201-S205.

At step S201, a brightness value set of a displayed image is determined,where the brightness value set includes brightness values of differentpixels of the displayed image.

At step S202, a regional brightness value set is generated by dividingthe pixels into a preset number of regions, where each region includesbrightness values of at least one pixel.

For example, data of four points is down-sampled to data of one point.That is, pixels of 3840*2180 are divided into small regions of1920*1080, and each region is as shown in FIG. 19.

At step S203, a maximum value and an average value of each regionalbrightness value in the regional brightness value set are determinedrespectively.

A method of calculating the regional brightness includes stepsS2031-S2032.

At step S2031, Py-sum and Py-avg in the region are calculated, andPy-max and Py-mid in the region are determined. Py-sum is a sum ofbrightnesses of the pixels, Py-max is a maximum brightness value of thepixel, Py-avg is an average brightness value of the pixel, and Py-mid isa middle brightness value of the pixel.

A method of determining Py-max and Py-mid includes: determining Py-maxby placing Y1, Y2, Y3 and Y4 in an ascending or descending order. Themiddle value Py-mid of four pieces of brightness data is an averagevalue of two pieces of brightness data in the middle, or any one of twopieces of brightness data in the middle.

At step S2032, index_(brightness) is calculated according toindex_(brightness)=(a×Py-max+b×Py-avg+c×Py-mid+512)>>10, where theindex_(brightness) is the regional brightness.

In the above formula, a, b and c are arbitrarily configured as long asa+b+c=1024 and a, b and c are all positive integers.

An example of the present disclosure provides a Py-mid displacementvaluing method. The method avoids a process of sorting brightnesses ofpixels, thereby reducing a data processing amount of a processor, andincreases an overall process speed.

A specific operation process includes steps S20321-S20323. At stepS20321, Py-sum and Py-avg in the region are calculated, and Py-max andPy-min in the region are determined. Py-sum is the sum of brightnessesvalue of the pixels, Py-max is the maximum brightness value of thepixels, Py-avg is the average brightness value of the pixels, and Py-minis a minimum brightness value of the pixels.

At step S20322, Py-mid is calculated according toPy-mid=(Py-sum=Py-max−Py-min+1)>>1, where the Py-mid is the middlebrightness value of the pixels.

At step S20323, index_(brightness) is finally calculated according toindex_(brightness)=(a×Py-max+b×Py-avg+c×Py-mid+512)>>10, where theindex_(brightness) is the regional brightness value. a, b and c arearbitrarily configured as long as a+b+c=1024 and a, b and c are allpositive integers.

The brightnesses of 3840*2180 pixels of the displayed image are combinedand converted into 1920*1080 regional brightnesses. The 1920*1080regional brightnesses form a regional brightness set, andcorrespondingly, the brightness of the displayed image is the set of the1920*1080 regional brightnesses.

In some examples of the present disclosure, 1920*1080 regionalbrightnesses are calibrated. Specifically, each value or some values ofthe regional brightness set is/are required to reach a target value (ameasured value by an instrument), and the brightness data reaching thetarget value is filled in the regional brightness set. Each regionalbrightness is calibrated if the displayed image is made to be accurate.

Generally, some fixed sampling points are calibrated in an engineeringimplementation. After the sampling points are determined (equally spacedor unequally spaced), other brightness values are obtained by aninterpolation method or a data fitting method.

A method of sampling specified curves is also used. For example, y=x,y=x^(γ), γ=2.2, 2.3, 0.45. Determination is performed according tocharacteristics of the display panel and finally-desired expressioncharacteristics.

At step S204, the regional brightness compensation factor is calculatedaccording to the maximum value and the average value of each regionalbrightness value.

The brightness compensation factor according to some examples of thepresent disclosure is an entire brightness compensation factor, or aregional brightness compensation factor. Accordingly, a correspondingcompensation method is an entire brightness enhancement method or aregional brightness enhancement method.

(1) The brightness compensation factor of the entire brightnessenhancement method is calculated as follows: the maximum brightnessvalue L max 1 and the average brightness value Lavg1 of the displayedimage are calculated. Specific operations may be referred to the aboveexamples, which will not be described herein.

The brightness compensation factor is calculated by substituting L max 1and Lavg1 into the brightness compensation factor model. Theconstruction manner of the brightness compensation factor model issimilar to the construction manner of the brightness compensation factormodel in the above examples. Therefore, a reference may be made to theabove examples.

Enhancement is performed for the data of the regional brightnessesindex_(brightness) respectively. The enhanced brightness data shall belimited within the data range if exceeding the range. Generally, for the8-bit data, if the data obtained by multiplying the brightness data byits respective y (the brightness compensation factor) is greater than255, the output brightness data is 255.

(2) The brightness compensation factor of the regional brightnessenhancement method is calculated as follows: the regional brightnesscompensation factor within each region is calculated respectively.

In some examples of the present disclosure, 3840*2180 pixels of thedisplayed image are converted into 1920*1080 regions. To improve anadjustment accuracy, the brightness compensation factor corresponding toeach region is calculated respectively in the examples of the presentdisclosure. Specifically, an average brightness value Lavg3 of eachregion and a maximum brightness value L max 3 of the region are firstlycalculated; the regional brightness compensation factor is calculated bysubstituting L max 3 and Lavg3 into the brightness compensation factormodel.

At step S205, the brightness drive signal corresponding to each regionis calculated according to the regional brightness compensation factorand the regional brightness value.

The regional brightness is enhanced, and a specific method ofcalculating the brightness drive signal is performed by multiplying eachregional brightness by the brightness compensation factor.

The brightness compensation factor according to some examples of thepresent disclosure is an entire brightness compensation factor, or aregional brightness compensation factor. Correspondingly, thecorresponding compensation method is an entire brightness enhancementmethod or a regional brightness enhancement method.

The step of calculating the brightness drive signal corresponding toeach region according to the regional brightness compensation factor andthe regional brightness includes: obtaining the brightness drive signalcorresponding to each region by compensating the regional brightnesscorresponding to each region according to the regional brightnesscompensation factor; and determining whether the brightness drive signalis greater than or equal to the maximum brightness value of the displayapparatus. If yes, the brightness drive signal is the maximum brightnessvalue of the display apparatus; if not, the brightness drive signal isobtained by calculation according to the regional brightnesscompensation factor and the regional brightness.

The enhanced brightness data may exceed a range, and thus is to belimited within the data range. Generally, for the 8-bit data, if thedata obtained by multiplying the brightness data by its respective y isgreater than 255, the output brightness data is 255.

The above descriptions are only specific examples of the presentdisclosure, but the scope of protection of the present disclosure is notlimited to the above descriptions. Any person skilled in the art mayeasily conceive of changes or substitutions within the technical scopedisclosed in the present disclosure, and such changes and substitutionsshall fall within the protection scope of the present disclosure.Therefore, the protection scope of the present disclosure shall besubject to the protection scope of the claims.

The invention claimed is:
 1. A dual-cell display apparatus, comprising:a first panel; a second panel disposed in a first preset order relativeto the first panel; a memory storing instructions; and a processor incommunication with the memory, wherein, when executing the instructions,the processor is configured to: receive an image signal, generatedimming data for the first panel according to the received image signal,and perform edge blurring processing before outputting the dimming data,generate image data for the second panel according to the received imagesignal, and generate backlight data for backlight control according tothe received image signal.
 2. The dual-cell display apparatus accordingto claim 1, wherein, when executing the instructions, the processor isconfigured to perform resolution reduction processing for the receivedimage signal.
 3. The dual-cell display apparatus according to claim 1,further comprising: a backlight module, comprising a plurality ofbacklight partitions.
 4. The dual-cell display apparatus according toclaim 3, further comprising: a backlight control processor configured togenerate control information for controlling the backlight moduleaccording to the backlight data; and a backlight driver configured todrive a backlight lamp on the backlight module according to the controlinformation.
 5. The dual-cell display apparatus according to claim 4,wherein the backlight control processor is further configured to:determine a backlight gain value according to an average backlight valueof the plurality of backlight partitions; and generate the controlinformation according to the backlight gain value.
 6. The dual-celldisplay apparatus according to claim 4, wherein the backlight controlprocessor is further configured to: divide the plurality of backlightpartitions into a plurality of backlight regions; determine a backlightgain value according to an average backlight value of each of theplurality of backlight regions; and generate the control informationaccording to each backlight gain value.
 7. The dual-cell displayapparatus according to claim 1, wherein, when executing theinstructions, the processor is configured to: generate the backlightdata for the backlight control according to the dimming data.
 8. Thedual-cell display apparatus according to claim 7, wherein, whenexecuting the instructions, the processor is configured to: generate thebacklight data for the backlight control by performing resolutionreduction processing and time filtering processing for the dimming data.9. The dual-cell display apparatus according to claim 1, wherein, whenexecuting the instructions, the processor is configured to: generate theimage data for the second panel by performing image compensationprocessing according to the dimming data.
 10. The dual-cell displayapparatus according to claim 1, wherein: the first panel comprises afirst polarizer and a second polarizer, a polarization direction of thefirst polarizer and a polarization direction of the second polarizer areperpendicular to each other; and the second panel comprises a thirdpolarizer and a fourth polarizer, a polarization direction of the thirdpolarizer and the polarization direction of the second polarizer areparallel to each other, and the polarization direction of the thirdpolarizer and a polarization direction of the fourth polarizer areperpendicular to each other.
 11. The dual-cell display apparatusaccording to claim 1, wherein: the first panel comprises a firstpolarizer and a second polarizer, a polarization direction of the firstpolarizer and a polarization direction of the second polarizer areperpendicular to each other, the second panel comprises a fourthpolarizer, a polarization direction of the fourth polarizer and thepolarization direction of the second polarizer are perpendicular to eachother.
 12. The dual-cell display apparatus according to claim 1, whereinthe first panel is further configured to: receive a brightness drivesignal; and adjust a transmittance of a pixel of the first panelaccording to the brightness drive signal.
 13. A dual-cell displayapparatus, comprising: a first panel; a second panel disposed in a firstpreset order relative to the first panel; a memory storing instructions;a processor in communication with the memory, wherein, when executingthe instructions, the processor is configured to: receive an imagesignal, generate dimming data for the first panel according to thereceived image signal, generate image data for the second panelaccording to the received image signal, and generate backlight data forbacklight control according to the received image signal; and whereinthe second panel is further configured to: receive a color drive signal;and adjust an RGB value of a pixel of the second panel according to thecolor drive signal.
 14. A dual-cell display apparatus, comprising: afirst panel; a second panel disposed in a first preset order relative tothe first panel; a memory storing instructions; a processor incommunication with the memory, wherein, when executing the instructions,the processor is configured to: receive an image signal, generatedimming data for the first panel according to the received image signal,generate image data for the second panel according to the received imagesignal, and generate backlight data for backlight control according tothe received image signal; and wherein: the first panel furthercomprises a first transmission region and a second transmission region,the first panel is configured to transmit light received from abacklight module to the second panel as background light; and atransmittance of the first transmission region is different from atransmittance of the second transmission region.